Firing pin retracting mechanism



July 23, 1957 o. D. HOOPES FIRING PIN RETRACTING MECHANISM 4 Sheets-Sheet 1 Filed Sept. 4, 195

INVENTOR.

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FIRING PIN RETRACTING MECHANISM Filed Sept. 4,. 1953 4 Sheets-Sheet 2 17 INVENTOR. DWEI'LJILHDD e5 ATTOENE Y5 July 23, 1957 o. D. HOOPES FIRING PIN RETRACTING MECHANISM 4 Sheets-Sheet 5 Filed Sept. 4, 1953 I mmvrozc ElywarL D HDD FEE| if 6 +41% pQW ATTORNEYS July 23, 1957 o. D. HOOP-ES FIRING PIN RETRACTING MECHANISM 4 4 SheetsSheet 4 Filed Sept. 4, 1955 INVENTOR. Ewen D HCI 1:11:25

;I A-rroFz/vEYs' FIREJG PIN RETRACTING MECHANISM Owen D. Hoopes, Latham, N. Y., assignor to the United States of America as represented by the Secretary of the Army 7 Application September 4, 1953, Serial No. 378,695

4 Claims. (Cl. 89-48) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to improvements in breechblocks and firing mechanisms for cannons and is particularly directed to electric firing mechanisms for cannons provided with vertically reciprocating breechblocks.

It has been found desirable that the cartridges used in cannons be provided with electrically fired primers wherever possible so as to reduce the hazard of accidental explosions due to mishandling, which exists with cartridges provided with percussion fired primers.

There are three conventional types of firing pins provided for cannons which have a vertically reciprocating breechblock and are adapted to fire electrically fired cartridges. They are, namely, wiper, solenoid operated and mechanically retracted types. In those firing mechanisms which embody wiper-type firing pins, the firing pin protrudes resiliently from the front face of the breechblock and is arranged to wipe the rear face of the chambered cartridge as the breechblock moves to firing position, making contact with the primer when the firing position is reached. A disadvantage of this type of firing mechanism is that the contact point of the firing pin must be blunt so as to prevent damage thereto while wiping across the rear face of the cartridge during the opening and closing of the breechblock. This enforced bluntness, it is obvious, impairs the electrical connection between the firing pin and the primer.

In those firing mechanisms which embody solenoid operated firing pins, the firing pin is held retracted in the breechblock by spring means until urged by the solenoid into contact with the cartridge primer when the firing mechanism is operated to fire the cartridge. The recoil of the cannon is arranged to open the electrical circuit to the solenoid, thus permitting the retracting spring to return the firing pin within the breechblock and thereby protect it during the movement of the breechblock; With this type of firing mechanism, the contact point of the firing pin may be quite sharp, to assure a goodc'ontact with the cartridge primer, as it is protected from damage during movement of the breechblock. A'dis'advantage of solenoid operated firing pins is that the solenoid requires more electrical power for operation than that required to ignite the primer. Therefore, in installations in tanks, where it is desirable to have an emergency power source separate from the tanks power plant to enable operation of the guns in event of failure of the vehicles electrical power source, the increased space required for the larger power plant is undesirable, as space in tanks is at a premium.

The firing systems which embody a mechanically retracted firing pin are the most desirable as the firingpin is retracted into the breechblock during movement thereof, permitting a sharp contact point, and it permits the use of'a powerful spring to press the firing pin into contact with the cartridge primer. Further, this system does not require electrical power to move the firing ,pin'into rates atent O 2,800,057 Patented July 23, 1957 contact position. However, in existing types of mechanically retracted firing pins the conventional retracting means is a bell crank lever which extends from the operating crank, normally positioned forwardly of the breechblock, back through the underside of the breechblock and up to the firing pin. This installation results in having to remove considerable stock from the portion of the breechblock which abuts the rear end of the chambered cartridge and therefore receives the greatest impact when the cartridge is fired. Consequently, the bulk of the breechblock has to be increased to give it the required strength, and this results in increased dimensions of the breech ring, which is undesirable in tank installations.

It is, therefore, a specific object of this, invention to provide for cannons having vertically reciprocating breechblocks, improved means for mechanically retracting firing pins thereinto.

It is a further object of this invention to provide a breechblock and means for mechanically retracting a firing pin thereinto, which permit the dimensions of the breech portion of a cannon to be reduced.

It is a still further object of this invention to provide a device for mechanically retracting a reciprocating firing pin, comprising easily manufactured components which require simple and conventionally accepted machine cuts in the breechblock for their installation.

It is another and still further object of this invention to provide a mechanism for retracting reciprocating firing pins whereby-the rotational movement of the cannons operating crank is translated to linear movements of a spring-biased operating rod which traverses the breechblock to the firing pin to provide movement thereof.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of the preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a perspective view of a cannon embodying a vertically reciprocating breechblock;

Fig. 2 is an exploded view of the operating crank assembly;

, Fig. 3 is a longitudinal cross-sectional view of the breech mechanism showing the breechblock in firing position with the loading position thereof in phantom;

Fig.4 is a view similar to Fig. 3 but showing the breech block midway between loading position and firing position;

Fig. 5 is a. fragmentary partially'cross-sectioned view ofthe breechblock, breech ring and cannon mount showing the electrical connections; and

Fig. 6 is a longitudinal cross-sectional view of the firing pin.

Shown in the figures is a breechblock 12, a tube 13 and a breech ring 14 which is provided with a vertical passageway 15. Breech ring 14 and tube 13 are assembled 'by conventional means and breechblock 12 is mounted in passageway 15 for slidable movement between an upward firing position and a downward loading position.

iTh'e'bottom side of breechblock 12 inclines upwardly and forwardly and depending therefrom is a pair of iongitudinally disposed L-shaped lugs 16 which'form therewith a'longitudinal T-slot 17. Provided laterally through breech ring 14, forwardly of passageway 15 'and' approximately. central thereof, is a rotatably mounted splined operating shaft 20. Mounted On operating shaft 20 is an operating crank 22. Operating crank 22 is provided with a cylindrical sleeve portion 21, which is splined internally to mate with the splines on operating shaft 20, and an arcuately formed crank portion 18, which extends tangentially from sleeve portion 21. One end of crank portion 18, is terminated by a planar surface 23, which is arranged to engage a mating surface on the underside of breech ring 14 to limit the downward rotation of operating crank 22. The other end of crank portion 18 is terminated by a laterally arranged semi-cylindrical portion 28. A cylindrical pin 25 is mounted through portion 28 with ends 26 extending laterally therefrom. A pair of cylindrical cross heads 30 are rotatably mounted on ends 26 and are arranged to be slidably received in T-slot 17 whereby rotation of operating shaft 20 causes operating crank 22 to raise or lower breechblock 12 in passageway 15. Operating shaft 20 is linked by conventional means (not shown) to cannon mount 90 so that breechblock 12 is automatically moved to loading position during the counter-recoil of the cannon. During rotation of operating crank 22, cross heads 30 are moved upwardly or downwardly in T- slot 17 and are arranged to be at the lower end thereof when the centers of operating shaft 26 and pin are in perpendicular alignment to the vertical plane of breechblock 12, as shown in Fig. 4, which is when breechblock 12 is approximately midway of the loading and firing positions.

When breechblock 12 is in the firing position, cross heads 30 are in the top forward end of T-slot 17 and engage the rear face of tube 13. At the same time, operating crank 22 is so positioned that the centers of pin 25 and operating shaft 20 are approximately a degree forwardly out of perpendicular alignment with the underside of breechblock 12. Thus, the weight of breechblock 12 against cross heads 30 urges operating crank 22 forwardly against tube 13 and into an interlock position whereby breechblock 12 is prevented from accidentally dropping from firing position. Arranged in line with the centers of pin 25 and operating shaft 20 is a V- recess 39 which extends laterally across the upper surface of semi-cylindrical portion 28. I

A firing pin 40 is mounted in breechblock 12 for longitudinal movement between a forward cartridge contacting position and a rearward retracting position. Firing pin 40 is provided with a body member 41 which conducts electrical current from a contact member 42 in breechblock 12 to the primer of a cartridge 43 chambered in tube 13. Body member 41 comprises a rod portion 44 which is terminated at the front end by a sharply pointed contact portion 45, and at the rear end by a cylindrical cup portion 46 which opens rearwardly. A steel sleeve member 47 encases rod portion 44 approximately to contact portion and has a circular flange portion 38 which conforms to the front face of cup portion 46. An insulating sleeve 48 provides a barrier between body member 41 and sleeve member 47 and an insulating cup-like member 49 protects the inside of cup portion 46. Body member 41, insulating sleeve 48, insulating member 49 and sleeve 47 are cemented together to form a unitary assembly.

Provided in breechblock 12, in alignment with the bore of tube 13, is a longitudinal bore 50 which is arranged to slidably receive steel sleeve 47. An orifice 51 of smaller diameter than bore 50 projects forwardly therefrom to the front face of breechblock 12, permitting contact portion 45 to extend therethrough to contact the primer of cartridge 43 when firing pin 40 is in -thefor ward cartridge contacting position. Orifice 51 is slightly larger than rod portion 44 to prevent electrical contact between rod portion 44 and breechblock 12.

A chamber 52 rearwardly adjoins bore 50 to receive cup portion 46 and is slightly larger than cup portion 46 so as to prevent electrical contact between body portion 51 and breechblock 12. A shoulder 53, formed by the junction of bore 50 and chamber 52, provides a forward stop for firing pin 40. A cylindrical retainer 55, having a centrally located cylindrical pocket 56 in the front side thereof, is releasably mounted in a mating opening 57 provided in the rear end of breechblock 12 adjoining chamber 52. One end of a helical spring 58 is received by pocket 56 and the other end by cup portion 46 so as to normally bias firing pin 40 to the cartridge contacting position.

A cylindrical tunnel 60 extends forwardly from the rear face of breechblock 12 to an end wall 61 located forwardly of shoulder 53. Tunnel 60 is located below and parallel to chamber 52 and forms a longitudinal intersection therewith. A vertical slot 63 provides communication between tunnel 60 and bore 56. Received in tunnel 60 is a cylindrical guide member 64 which is retained therein between end wall 61 and retainer 55. The front end of guide member 64 is bifurcated by a crevice 65 having vertical, parallel walls, and a channel 66 extends longitudinally along the forward upper portion of guide member 64 to communicate with crevice 65. A pin 67 is mounted through guide member 64 so as to traverse channel 66. An actuator 63 is pivotally mounted at the rear end thereof on pin 67 and is receivable by channel 66 and crevice 65. A lug portion 69 projects upwardly from the front end of actuator 68 into slot 63 and is arranged to engage flange 38 whereby firing pin 40 is movable to the retracted position when actuator 68 is acted upon by a push rod 70. The engagement of lug portion 69 with the walls of slot 63 secures guide 64 against rotation.

Push rod 70 comprises a cylindrical plunger 71 and a rectangular base 72 fixed perpendicularly thereto. Plunger 71 is provided with a reduced diameter portion 73 which extends from an annular shoulder 75 to be received by crevice 65. Base 72 is arranged longitudinally in T-slot 17 so as to be engaged by semi-cylindrical portion 28 of operating crank 22 during movement thereof in T-slot 17 and the bottom side of such base is hollowed longitudinally as shown by 76. The end of base 72 adjacent plunger 71 inclines forwardly and upwardly to form an angular portion 77 receivable by V-recess 39.

A conduit 80 receives plunger 71 for slidable movement therein and is disposed perpendicularly to the bottom side of breechblock 12 so that angular portion 77 is seated in Vrecess 39 and reduced diameter section 73 is received by crevice 65 when breechblock 12 is in the firing position. Conduit 80 is provided with portions of different diameters which conform to the diameters of plunger 71 and formed thereby is an annular stop ledge 81 so arranged in relationship with shoulder 75 that a compression spring 82 mounted on reduced diameter section 73 and disposed therebetween biases push rod 70 against semi-cylindrical portion 28 of operating crank 22.

A receptacle 85 is arranged in the bottom side of breechblock 12 so as to receive base 72 when the rotation of operating crank 22 cams angular portion 77 upwardly out of V-recess 39 to the surface of semicylindrical portion 28, and base 72 is retained therein by the engagement of the surface of semi-cylindrical portion 28 as breechblock 12 moves between the firing and the loading positions. Plunger 71 is so adapted that when base 72 is received by receptacle 85, actuator 68 is pushed thereby against flange portion 38 of firing pin 40 which is urged against the bias of spring 58 to the retracting inoperative position. A screw 86 is threadably mounted in the bottom side of breechblock 12 rearwardly of receptacle 85 to secure a locking member 87 which is arranged to project forwardly into hollow 76 of base 72 to provide limited movement of push rod 76.

As has been previously mentioned, electrical current is conducted to firing pin 40 by contact member 42 in breechblock 12. Contact member 42 is resiliently mounted through breechblock 12 and is so arranged that one end slidably engages the outside surface of cup portion 46. The opposite end of contact 42, noted by 59, projects into passageway 15 and is arranged to contact one end of a resiliently mounted connector member 88, which extends laterally through breech ring 14, when breechblock 12 is in the firing position. The opposite end of connector member 88, noted by 62, is arranged to be engaged by an electrical outlet 89 in cannon mount 90 when breech ring 14 is in battery position. Electrical outlet 89 is connectable through conventional operators and loaders switches (not shown) to an outside source of power (not shown).

Thus, when breechblock 12 is in the firing position, angular portion 77 is biased into V-recess 39 by spring 82 which relieves the tension of actuator 68 against firing pin 40. Thereby, helical spring 58 urges firing pin 40 forwardly to press contact portion 45 into engagement with the primer of cartridge 43. The sharp point of contact portion 45 and the tension of spring 58 assures positive electrical contact with the primer. At the same time, firing pin 40 is in engagement with contact member 42 which is connected through connector 88 and electrical outlet 89 to the operators and loaders switches which when closed connect the primer to the outside source of power, causing cartridge 43 to be fired. When cartridge 43 is fired, breech ring 14 recoils in mount 90 to open the electrical circuit between electrical outlet 89 and connector 88, thus assuring that the electrical power is disconnected from firing pin 40 at the time that the connection between end 59 of contact 42 is disconnected from connector 88 when breechblock 12 is moved away from the firing position during counter-recoil to prevent electrical arcing between such connector and the side of breechblock 12 when wiping thereacross.

As has been explained, operating crank 22 is approximately a degree forwardly out of vertical alignment with the bottom side of breechblock 12 when in the firing position. Therefore, during the initial movement of operating crank 22, when cross heads 30 are being rotated from dead center, in respect to the base of breechblock 12, there is only a slight movement of breechblock 12 down passageway 15 but during that short space of travel angular portion 77 is carnmed out of V-recess 39 causing push rod 70 to move actuator 68 against firing pin 40 which is retracted to the protected inoperative position in breechblock 12. Firing pin 40 is maintained in the retracted inoperative position by the engagement of semicylindrical portion 28 with base 72 of push rod 70 as operating crank 22 moves up and down T-slot 17 to move breechblock 12 to or from loading position.

It is readily apparent from the foregoing description that there is here provided a firing mechanism having certainty of operation and requiring few and simple cuts machined in the breechblock for its installation, thus enabling the thickness of the breechblock to be brought to a minimum and the bulk of the cannons breech reduced.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In a weapon having a breech ring and a cartridge receiving tube assembled thereto, a breechblock mounted in said breech ring for movement between a firing position and a loading position, said breechblock being provided with a longitudinal bore axially aligned with said tube, a cylindrical tunnel disposed parallel with said bore and arranged to partially intersect with the lower portion thereof and a cylindrical conduit extending from the front end of said tunnel to the bottom side of said breechblock, a firing pin mounted in said bore for movement between a retracting position and a cartridge contacting position and provided with an annular flange, a spring for normally biasing said firing pin to said cartridge contacting position, a guide member received by said tunnel, said guide member being provided with a vertical crevice in the forward end thereof and a longitudinal channel extending therefrom along the upward portion of said guide member, an actuator pivotally mounted at one end to said guide member in said crevice for movement against said flange and being receivable by said channel, a push rod slidably mounted in said conduit and arranged to be received by said crevice for engagement with said actuator, crank means for moving said breechblock between said loading and said firing position, and a semicylindrical portion on said crank means having sliding engagement with said push rod whereby said push rod is urged thereby against said flange to hold said firing pin in said retracting position when said breechblock is away from said firing position.

2. In a weapon having a breech ring and a cartridge receiving tube assembled thereto, a breechblock mounted in the breech ring for sliding movement between a firing position and a loading position, said breechblock being provided with a longitudinal bore, an upwardly and forwardly disposed T-slot along the underside thereof, a longitudinal tunnel partially intersecting said bore, a cylindrical conduit disposed between the forward portion of said T-slot and the forward portion of said tunnel and a rectangular receptacle provided in said T-slot rearwardly of said conduit, a firing pin mounted in said bore for longitudinal movement between a retracting position and a cartridge contacting position, said firing pin being provided with an electrical contact and an annular flange, a spring for normally biasing said firing pin to said cartridge contacting position, a cylindrical guide member mounted in said tunnel, an actuator mounted in said guide member for pivotal movement and adapted to engage said flange, a push rod slidably received by said conduit and having a base portionreceivable by said receptacle, said rod being adapted for moving said actuator against said flange when said base is received by said receptacle whereby said firing pin is urged to said retracting position, resilient means for biasing said rod from said actuator, crank means having a pair of cross heads slidably received in said T-slot for moving said breechblock between said firing and said loading positions, said crank means having a terminating semi-cylindrical portion engageably cooperating with said base portion for urging said base portion into said receptacle, a V-recess transversely disposed in said semi-cylindrical portion and adapted to receive one end of said base when said breechblock is in said firing position whereby said base portion is biased by said resilient means into said V-recess and partway out of said receptacle to retract said rod away from said actuator whereby said firing pin is biased by said spring to said cartridge contacting position, and electrical means for conducting electrical power to said contact when said breechblock is in said firing position.

3. In a firearm, a breechblock mounted in a breech ring for slidable movement between a loading position and a firing position, said breechblock being provided with an upwardly and forwardly inclining T-slot along the bottom side, a longitudinal bore, a cylindrical tunnel communicating longitudinally with the bottom portion of said bore and disposed parallel therewith and a cylindrical conduit leading from the front end of said T-slot to said tunnel, a shaft rotatably mounted in said breech ring, an operating crank pivotally mounted on said shaft with the free end thereof being slidably mounted in said T-slot for movement between the front and rear portions thereof during which movement said breechblock is actuated respectively between said firing position and said loading position and said operating crank being rotatable to an overtravel position slightly beyond top dead center relative to said breechblock after said breechblock is actuated to said firing position, a push rod having a plunger portion slidably received by said conduit and a base portion disposed longitudinally along said T-slot for engagement with said free end of said operating crank when moving between said front portion and said rear portion of said T-slot, cam means on said free end of said operating crank cooperable with said push rod for actuation thereof when said operating crank is between said top dead center and said overtravel position, a firing pin slidably mounted in said bore, and a pivotal actuator mounted in said tunnel having engagement with said plunger portion and said firing pin for translating movement of said push rod to said firing pin.

4. In a firearm, a breechblock mountedin a breech ring for slidable movement between a loading position and a firing position, said breechblock being provided the front and rear portions thereof to actuate said breechblock between said firing position and said loading position respectively and being movable to an overtravel position slightly forward of top dead center relative to said shaft after said breechblock is moved to said firing position for locking said breechblock in said firing position, afiring pin having an annular flange mounted in said bore for slidable movement between a retracting position and a cartridge contacting position, a spring for normally biasing said firing pin to said cartridge contacting position, a pivotal actuator member mounted in tunnel for movement against said flange to actuate said firing pin to said retracting position, a push rod slidably mounted in said conduit for engageable cooperation with said actuator and said semicylindrical portion whereby said firing pin is held in saidretracting position when said breechblock is away from said firing position, and a /-slot in said semicylindrical portion for receiving said push rod when saidcross-heads are in said overtravel position whereby said push rod is longitudinally responsive to rotation of said operating crank for actuation of said firing pin between said retracting and cartridge contacting positions while said breechblock is practically unresponsive to rotation of said operating crank.

References Cited in the file of this patent UNITED STATES PATENTS 1,040,001 Allsson Oct. 1, 1912 1,076,875 Driggs Oct. 28, 1913 1,290,835 Jakobsson Jan. 7, 1919 2,164,700 Coffman s July 4, 1939 2,489,954 Burney Nov. 29, 1949 

